Embodiments of the present invention relate to repairing surface defects in, and cleaning residues off, surfaces of a component exposed to plasma processes.
In the manufacture of integrated circuits and displays, semiconductor, dielectric and conductor materials are formed on a substrate and etched to form patterns of active and passive features. These materials are typically formed by plasma processes which use an energized gas, such as chemical vapor deposition (CVD), physical vapor deposition (PVD), ion implantation processes, and etching processes. In CVD processes, a reactive gas is used to deposit a layer of material on the substrate; and in PVD processes, a target is sputtered to deposit material on the substrate. In ion implantation processes, ions are implanted into the substrate to dope semiconducting material to form features having altered electronic properties. In etching processes, a patterned etch-resistant mask of photoresist and/or a hard mask is formed on the substrate by photolithographic methods, and the exposed portions of the substrate are etched by an energized gas.
The energized gas for the plasma can be energized by electrical energy, microwaves, or other energy carriers. When an energized gas is used to etch or deposit material on a substrate in a chamber, process residues often form on the surfaces of components in the substrate processing chamber. Accumulated process residues can flake off from chamber surfaces and fall upon and contaminate the substrate while it is being processed. Certain process residues can also corrode the component surfaces, requiring their frequent replacement. Accumulated process residues formed during one process, can also react with the process gases or residues formed in another process, preventing different processes from being run in the same chamber for mixed application productions.
Conventional chamber cleaning processes, which are periodically performed to clean process residues off interior chamber surfaces, often fail to properly clean off the residues. In wet cleaning processes, an operator manually scrubs down chamber surfaces with a residue dissolving solvent to clean the chamber surfaces. However, the day-to-day variability in such processes can affect the quality, and reproducibility, of cleaning. Also, the wet cleaning scrubbing material or solvent can contaminate the chamber. Instead of scrubbing the component surfaces with an abrasive scrubber, which often scratches the surfaces of the components with uneven gouges, the components can also be bead blasted to clean process residues formed on the component surfaces and provide a textured surface. However, aggressive grit blasting can create deep pits and scratches in the surfaces of the chamber components. Also, chamber components having complex shapes and small dimensions are difficult to clean by bead blasting as the grit blasting nozzle cannot be easily maneuvered around these complex shapes.
In plasma or dry cleaning processes, a cleaning gas energized by RF or microwave energy is used to clean process residues formed in the chamber. This process allows cleaning of the chamber components in-situ so that the chamber does not have to be dismantled into its components. However, plasma cleaning processes often fail to effectively clean residues off certain components, such as for example, residues formed on the sidewalls of gas distribution holes of components such as a gas distributor showerhead. It is not known why these components are not properly cleaned by the plasma process, when other internal chamber surfaces, such as the surfaces of the chamber itself, are effectively cleaned by the same process. Improper cleaning could be occurring because the cleaning plasma is formed between the RF biased gas distributor and substrate support, and not within the holes of the gas distributor showerhead itself. Also, the distal location of the exhaust port causes the plasma species to be rapidly drawn away from the holes of the gas distributor to limit exposure of residues formed in the holes of the showerhead to the cleaning gas plasma. As a result, conventional in-situ cleaning gas plasmas do not effectively clean the holes and internal surfaces of components such as the gas distributor showerhead.
Surface microcracks on ceramic surfaces of chamber components can also generate particles from cracked and flaked off surface grains. However, conventional surface repairing processes, which are used to repair micro-cracks on the surfaces of ceramic materials, are expensive and time-consuming processes. The ceramic component would need to be processed individually, so that it would have to be detached from any metallic component, before shipping to a surface repairing facility. Accordingly, most surface repairing processes are done only when the ceramic component is first manufactured. For example, the silicon containing grains at the micro-cracks of ceramic surfaces are converted to silicon oxide by an oxidation process, such as thermal oxidation. Thereafter, the converted silicon oxide is removed by dipping the component in a hydrofluoric acid bath. However, this surface repairing process involves a large amount of time not only because of the slow rate of oxidation, but also because the surface repairing process requires multi-step sequences of surface oxidation/oxide removal to heal micro-cracks well below the surface of the ceramic component. The conventional surface repairing process can take many days to complete.
Contaminant particles also arise from damaged micro-crack regions of the component surface, that are not fully healed in the heat treatment oxidization and acid bath cleaning process. Large numbers of contaminant particles also arise from damaged regions caused by abrasive and aggressive cleaning methods used to clean the surfaces of the ceramic materials. Conventional heat treatment oxidization processes are limited in their ability to repair micro-cracks in the surface of these cleaned components because there is a saturation point at which the ceramic materials such as a silicon carbide surface forms a passive layer of silicon dioxide. Further formation of silicon dioxide to heal the cracks is difficult. An acid (Hydrofluoric Acid) bath stripping process can also be used to remove excess silicon dioxide and expose fresh silicon carbide layers for additional oxidization treatment. However, the multi-step oxidization and acid bath process requires the dismantling the ceramic component from any attached metallic component. As a result, surface repairing takes even longer to complete and increases the costs.
Thus it is desirable to have a process for thoroughly cleaning process residues from components exposed to plasma processes. It is also desirable to clean component surfaces without excessive surface damage or scratches. It is further desirable to have a cleaning process that is cost effective and reproducible.